Analytical Chemistry (journal)

Physics

Engineering

Faraday efficiency

Physical chemistry

Power (physics)

Electrode

Organic chemistry

Inorganic chemistry

Aqueous solution

Chemistry

Metallurgy

Materials science

Chemical engineering

Chromatography

Hydrogen

Zinc

Metal

Battery (electricity)

Quantum mechanics

Electrolyte

Anode

Advanced Materials

The hydrogen evolution in Zn metal battery is accurately quantified by in situ battery–gas chromatography–mass analysis. The hydrogen fluxes reach 3.76 mmol h−1 cm−2 in a Zn//Zn symmetric cell in each segment, and 7.70 mmol h−1 cm−2 in a Zn//MnO2 full cell. Then, a highly electronically insulating (0.11 mS cm−1) but highly Zn2+ ion conductive (80.2 mS cm−1) ZnF2 solid ion conductor with high Zn2+ transfer number (0.65) is constructed to isolate Zn metal from liquid electrolyte, which not only prohibits over 99.2% parasitic hydrogen evolution but also guides uniform Zn electrodeposition. Precisely quantitated, the Zn@ZnF2//Zn@ZnF2 cell only produces 0.02 mmol h−1 cm−2 of hydrogen (0.53% of the Zn//Zn cell). Encouragingly, a high-areal-capacity Zn@ZnF2//MnO2 (≈3.2 mAh cm−2) full cell only produces maximum hydrogen flux of 0.06 mmol h−1 cm−2 (0.78% of the Zn//Zn cell) at the fully charging state. Meanwhile, Zn@ZnF2//Zn@ZnF2 symmetric cell exhibits excellent stability under ultrahigh current density and areal capacity (10 mA cm−2, 10 mAh cm−2) over 590 h (285 cycles), which far outperforms all reported Zn metal anodes in aqueous systems. In light of the superior Zn@ZnF2 anode, the high-areal-capacity aqueous Zn@ZnF2//MnO2 batteries (≈3.2 mAh cm−2) shows remarkable cycling stability over 1000 cycles with 93.63% capacity retained at ≈100% Coulombic efficiency.

Toward Practical High‐Areal‐Capacity Aqueous Zinc‐Metal Batteries: Quantifying Hydrogen Evolution and a Solid‐Ion Conductor for Stable Zinc Anodes